where the minus sign in front is due to perturbative expansion with one interaction insertion (see Eq. (3.1) of [1]}, for example). Plugging in Eq. (REF ) and the massive quark energy denominator, we have
\(\left|\psi _{q \bar{q}}^{2}\right\rangle & =&\int _{\Lambda }^{e^{\delta Y} \Lambda }d k^{+} \int _{0}^{k^{+}} d p^{+} \int d^{2}\mathbf {k} d^{2}\mathbf {p}\left|\bar{q}_{\lambda _{2}}^{\beta }(k-p) q_{\lambda _{1}}^{\alpha }(p)\right\rangle \frac{g^{2} t_{\alpha \beta }^{a} \rho ^{a}(-\mathbf {k}) \chi _{\lambda _{1}}^{\dagger } \chi _{\lambda _2}}{8 \pi ^{3} k^{+2}\left(\frac{\mathbf {p}^{2}+m^{2}}{2 p^{+}}+\frac{(\mathbf {k}-\mathbf {p})^{2}+m^{2}}{2\left(k^{+}-p^{+}\right)}\right)} \nonumber \\\) 
